<template>
	<view class="k-menu-wrap">
		<scroll-view scroll-y scroll-with-animation class="u-tab-view menu-scroll-view" :scroll-top="scrollTop">
			<view
				v-for="(item, index) in tabbar"
				:key="index"
				class="u-tab-item"
				:class="[current == index ? 'u-tab-item-active' : '']"
				:data-current="index"
				@tap.stop="swichMenu(index)"
			>
				<text class="u-line-1">{{ item.name }}</text>
			</view>
		</scroll-view>
		<block v-for="(item, index) in tabbar" :key="index">
			<scroll-view scroll-y class="right-box" v-if="current == index">
				<view class="page-view">
					<view class="class-item">
						<view class="item-title">
							<text>{{ item.name }}</text>
						</view>
						<view class="item-container">
							<view class="thumb-box" v-for="(item1, index1) in item.children" :key="index1">
								<image class="item-menu-image" :src="item1.icon" mode=""></image>
								<view class="item-menu-name margin-top-sm">{{ item1.name }}</view>
							</view>
						</view>
					</view>
				</view>
			</scroll-view>
		</block>
	</view>
</template>

<script>
export default {
	props: {
		tabbar: {
			type: Array,
			default: () => []
		}
	},
	data() {
		return {
			scrollTop: 0, //tab标题的滚动条位置
			current: 0, // 预设当前项的值
			menuHeight: 0, // 左边菜单的高度
			menuItemHeight: 0 // 左边菜单item的高度
		};
	},
	methods: {
		async swichMenu(index) {
			if (this.current === index) return;
			this.current = index;
			// 如果为0，意味着尚未初始化
			if(this.menuHeight === 0 || this.menuItemHeight === 0){
				// 获取高度
				await this.getElRect('menu-scroll-view', 'menuHeight');
				await this.getElRect('u-tab-item', 'menuItemHeight');
			}
			// 将菜单菜单活动item垂直居中
			this.scrollTop = index * this.menuItemHeight + this.menuItemHeight / 2 - this.menuHeight / 2;
		},
		// 获取目标元素的高度
		getElRect(className,dataVal){
			new Promise((resolve, reject) => {
				const query = uni.createSelectorQuery().in(this);
				query.select('.' + className).fields({size: true},res => {
					// 如果节点尚未生成，res值为null，循环调用执行
					if(!res) {
						setTimeout(() => {
							this.getElRect(className);
						}, 10);
						return ;
					}
					this[dataVal] = res.height;
				}).exec();
			})
		}
	}
};
</script>

<style lang="scss" scoped>
.k-menu-wrap {
	height: 100%;
	display: flex;
	overflow: hidden;
	// 左侧
	.u-tab-view {
		width: 200rpx;
		height: 100%;
		.u-tab-item {
			height: 110rpx;
			background: #f6f6f6;
			box-sizing: border-box;
			display: flex;
			align-items: center;
			justify-content: center;
			font-size: 26rpx;
			color: #444;
			font-weight: 400;
			line-height: 1;
		}
		.u-tab-item-active {
			position: relative;
			color: #000;
			font-size: 30rpx;
			font-weight: 600;
			background: #fff;
		}
		.u-tab-item-active::before {
			content: '';
			position: absolute;
			border-left: 4px solid #2979ff;
			height: 32rpx;
			left: 0;
			top: 39rpx;
		}
	}
	// 右侧
	.right-box {
		background-color: #fafafa;
		.page-view {
			padding: 16rpx;
			.class-item {
				margin-bottom: 30rpx;
				background-color: #fff;
				padding: 16rpx;
				border-radius: 8rpx;
				// 标题
				.item-title {
					font-size: 30rpx;
					color: $u-main-color;
					font-weight: bold;
					margin: 10rpx 0;
				}
				.item-container {
					display: flex;
					flex-wrap: wrap;
					.thumb-box {
						width: 33.333333%;
						display: flex;
						align-items: center;
						justify-content: center;
						flex-direction: column;
						margin-top: 20rpx;
						margin-bottom: 10rpx;
						// 图标
						.item-menu-image {
							width: 120rpx;
							height: 120rpx;
							border-radius: 100rpx;
						}
						// 文字
						.item-menu-name {
							font-weight: normal;
							font-size: 24rpx;
							color: $u-main-color;
						}
					}
				}
			}
		}
	}
}
</style>
